From: Suresh K C suresh.k.chandrappa@gmail.com
Add a test case to verify cachestat behavior with memory-mapped files using mmap(). This ensures that pages accessed via mmap are correctly accounted for in the page cache.
Also add a test for /proc/cpuinfo to validate cachestat's handling of virtual files in pseudo-filesystems. This improves test coverage for edge cases involving non-regular files.
Tested on x86_64 with default kernel config.
Signed-off-by: Suresh K C suresh.k.chandrappa@gmail.com --- .../selftests/cachestat/test_cachestat.c | 69 ++++++++++++++++++- 1 file changed, 67 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/cachestat/test_cachestat.c b/tools/testing/selftests/cachestat/test_cachestat.c index 632ab44737ec..81e7f6dd2279 100644 --- a/tools/testing/selftests/cachestat/test_cachestat.c +++ b/tools/testing/selftests/cachestat/test_cachestat.c @@ -22,7 +22,7 @@
static const char * const dev_files[] = { "/dev/zero", "/dev/null", "/dev/urandom", - "/proc/version", "/proc" + "/proc/version","/proc/cpuinfo","/proc" };
void print_cachestat(struct cachestat *cs) @@ -202,6 +202,65 @@ static int test_cachestat(const char *filename, bool write_random, bool create, return ret; }
+bool test_cachestat_mmap(void){ + + size_t PS = sysconf(_SC_PAGESIZE); + size_t filesize = PS * 512 * 2;; + int syscall_ret; + size_t compute_len = PS * 512; + struct cachestat_range cs_range = { PS, compute_len }; + char *filename = "tmpshmcstat"; + unsigned long num_pages = compute_len / PS; + struct cachestat cs; + bool ret = true; + int fd = open(filename, O_RDWR | O_CREAT | O_TRUNC, 0666); + if (fd < 0) { + ksft_print_msg("Unable to create mmap file.\n"); + ret = false; + goto out; + } + if (ftruncate(fd, filesize)) { + ksft_print_msg("Unable to truncate mmap file.\n"); + ret = false; + goto close_fd; + } + if (!write_exactly(fd, filesize)) { + ksft_print_msg("Unable to write to mmap file.\n"); + ret = false; + goto close_fd; + } + char *map = mmap(NULL, filesize, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); + if (map == MAP_FAILED) { + ksft_print_msg("mmap failed.\n"); + ret = false; + goto close_fd; + } + + for (int i = 0; i < filesize; i++) { + map[i] = 'A'; + } + map[filesize - 1] = 'X'; + + syscall_ret = syscall(__NR_cachestat, fd, &cs_range, &cs, 0); + + if (syscall_ret) { + ksft_print_msg("Cachestat returned non-zero.\n"); + ret = false; + } else { + print_cachestat(&cs); + if (cs.nr_cache + cs.nr_evicted != num_pages) { + ksft_print_msg("Total number of cached and evicted pages is off.\n"); + ret = false; + } + } + +close_fd: + close(fd); + unlink(filename); +out: + return ret; +} + bool test_cachestat_shmem(void) { size_t PS = sysconf(_SC_PAGESIZE); @@ -274,7 +333,7 @@ int main(void) ret = 1; }
- for (int i = 0; i < 5; i++) { + for (int i = 0; i < 6; i++) { const char *dev_filename = dev_files[i];
if (test_cachestat(dev_filename, false, false, false, @@ -315,5 +374,11 @@ int main(void) ret = 1; }
+ if (test_cachestat_mmap()) + ksft_test_result_pass("cachestat works with a mmap file\n"); + else { + ksft_test_result_fail("cachestat fails with a mmap file\n"); + ret = 1; + } return ret; }
On Sat, May 24, 2025 at 1:36 AM Suresh K C suresh.k.chandrappa@gmail.com wrote:
From: Suresh K C suresh.k.chandrappa@gmail.com
Add a test case to verify cachestat behavior with memory-mapped files using mmap(). This ensures that pages accessed via mmap are correctly accounted for in the page cache.
Also add a test for /proc/cpuinfo to validate cachestat's handling of virtual files in pseudo-filesystems. This improves test coverage for
Hmm, it's been awhile since I wrote these tests, but isn't there already a test for /proc/* files?
edge cases involving non-regular files.
Tested on x86_64 with default kernel config.
Signed-off-by: Suresh K C suresh.k.chandrappa@gmail.com
.../selftests/cachestat/test_cachestat.c | 69 ++++++++++++++++++- 1 file changed, 67 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/cachestat/test_cachestat.c b/tools/testing/selftests/cachestat/test_cachestat.c index 632ab44737ec..81e7f6dd2279 100644 --- a/tools/testing/selftests/cachestat/test_cachestat.c +++ b/tools/testing/selftests/cachestat/test_cachestat.c @@ -22,7 +22,7 @@
static const char * const dev_files[] = { "/dev/zero", "/dev/null", "/dev/urandom",
"/proc/version", "/proc"
"/proc/version","/proc/cpuinfo","/proc"};
void print_cachestat(struct cachestat *cs) @@ -202,6 +202,65 @@ static int test_cachestat(const char *filename, bool write_random, bool create, return ret; }
+bool test_cachestat_mmap(void){
size_t PS = sysconf(_SC_PAGESIZE);size_t filesize = PS * 512 * 2;;int syscall_ret;size_t compute_len = PS * 512;struct cachestat_range cs_range = { PS, compute_len };char *filename = "tmpshmcstat";unsigned long num_pages = compute_len / PS;struct cachestat cs;bool ret = true;int fd = open(filename, O_RDWR | O_CREAT | O_TRUNC, 0666);if (fd < 0) {ksft_print_msg("Unable to create mmap file.\n");ret = false;goto out;}if (ftruncate(fd, filesize)) {ksft_print_msg("Unable to truncate mmap file.\n");ret = false;goto close_fd;}if (!write_exactly(fd, filesize)) {ksft_print_msg("Unable to write to mmap file.\n");ret = false;goto close_fd;}char *map = mmap(NULL, filesize, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);if (map == MAP_FAILED) {ksft_print_msg("mmap failed.\n");ret = false;goto close_fd;}for (int i = 0; i < filesize; i++) {map[i] = 'A';}map[filesize - 1] = 'X';syscall_ret = syscall(__NR_cachestat, fd, &cs_range, &cs, 0);if (syscall_ret) {ksft_print_msg("Cachestat returned non-zero.\n");ret = false;} else {print_cachestat(&cs);if (cs.nr_cache + cs.nr_evicted != num_pages) {ksft_print_msg("Total number of cached and evicted pages is off.\n");ret = false;}}+close_fd:
close(fd);unlink(filename);+out:
return ret;+}
This looks 90% the same as another test. Are we literally just adding the mmap step to test_cachestat and call it a new test?
Can we at least refactor things?
linux-kselftest-mirror@lists.linaro.org
-
Nhat Pham -
Suresh K C